As known, the photocatalyst is a light-activated catalyst which catalyzes a chemical reaction under light irradiation. For example, TiO2, ZnO, SnO2, ZrO2, CdS and ZnS are common photocatalysts, wherein TiO2 has stable chemical property and strong oxidation ability, so it is the major photocatalyst available in the market, and can be used for deodorization, cleaning and sterilization under visible light or UV light irradiation.
In addition, the silver catalyst, such as silver chloride, is another widely-used photocatalyst. The sterilization mechanism of silver chloride is that when it is under UV light irradiation, the interior electrons of silver chloride jump from the valence band to the conduction band and thus the electron-hole pairs are generated, which further oxidize the hydroxide ions ionized from water molecule into the hydroxyl free radicals. Since the hydroxyl free radicals have strong oxidation ability, they are able to decompose organic substances and destroy cell walls and DNA of bacteria, and thus have deodorization, cleaning and sterilization effects.
The conventional method of fabricating the silver chloride film is to obtain the solid precipitants of silver chloride by reacting the silver nitrate aqueous solution and the sodium chloride aqueous solution, and then coat the solid silver chloride onto a substrate by sol-gel and spin coat techniques to form the silver chloride film. However, the resulted silver chloride film is a flat film having a relatively smaller specific surface area, so the active area thereof is limited, and thus the silver chloride film has limited effects for deodorization, cleaning and sterilization.
Therefore, it is an important issue to improve the method of fabricating the film to increase the specific surface area thereof so as to overcome the defects of the prior art.